import os
from io import BytesIO, StringIO, UnsupportedOperation
from django.core.files.utils import FileProxyMixin
from django.utils.functional import cached_property
[文档]class File(FileProxyMixin):
DEFAULT_CHUNK_SIZE = 64 * 2 ** 10
def __init__(self, file, name=None):
self.file = file
if name is None:
name = getattr(file, 'name', None)
self.name = name
if hasattr(file, 'mode'):
self.mode = file.mode
def __str__(self):
return self.name or ''
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self or "None")
def __bool__(self):
return bool(self.name)
def __len__(self):
return self.size
@cached_property
def size(self):
if hasattr(self.file, 'size'):
return self.file.size
if hasattr(self.file, 'name'):
try:
return os.path.getsize(self.file.name)
except (OSError, TypeError):
pass
if hasattr(self.file, 'tell') and hasattr(self.file, 'seek'):
pos = self.file.tell()
self.file.seek(0, os.SEEK_END)
size = self.file.tell()
self.file.seek(pos)
return size
raise AttributeError("Unable to determine the file's size.")
[文档] def chunks(self, chunk_size=None):
"""
Read the file and yield chunks of ``chunk_size`` bytes (defaults to
``File.DEFAULT_CHUNK_SIZE``).
"""
chunk_size = chunk_size or self.DEFAULT_CHUNK_SIZE
try:
self.seek(0)
except (AttributeError, UnsupportedOperation):
pass
while True:
data = self.read(chunk_size)
if not data:
break
yield data
[文档] def multiple_chunks(self, chunk_size=None):
"""
Return ``True`` if you can expect multiple chunks.
NB: If a particular file representation is in memory, subclasses should
always return ``False`` -- there's no good reason to read from memory in
chunks.
"""
return self.size > (chunk_size or self.DEFAULT_CHUNK_SIZE)
[文档] def __iter__(self):
# Iterate over this file-like object by newlines
buffer_ = None
for chunk in self.chunks():
for line in chunk.splitlines(True):
if buffer_:
if endswith_cr(buffer_) and not equals_lf(line):
# Line split after a \r newline; yield buffer_.
yield buffer_
# Continue with line.
else:
# Line either split without a newline (line
# continues after buffer_) or with \r\n
# newline (line == b'\n').
line = buffer_ + line
# buffer_ handled, clear it.
buffer_ = None
# If this is the end of a \n or \r\n line, yield.
if endswith_lf(line):
yield line
else:
buffer_ = line
if buffer_ is not None:
yield buffer_
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, tb):
self.close()
[文档] def open(self, mode=None):
if not self.closed:
self.seek(0)
elif self.name and os.path.exists(self.name):
self.file = open(self.name, mode or self.mode)
else:
raise ValueError("The file cannot be reopened.")
return self
[文档] def close(self):
self.file.close()
[文档]class ContentFile(File):
"""
A File-like object that takes just raw content, rather than an actual file.
"""
def __init__(self, content, name=None):
stream_class = StringIO if isinstance(content, str) else BytesIO
super().__init__(stream_class(content), name=name)
self.size = len(content)
def __str__(self):
return 'Raw content'
def __bool__(self):
return True
def open(self, mode=None):
self.seek(0)
return self
def close(self):
pass
def write(self, data):
self.__dict__.pop('size', None) # Clear the computed size.
return self.file.write(data)
def endswith_cr(line):
"""Return True if line (a text or bytestring) ends with '\r'."""
return line.endswith('\r' if isinstance(line, str) else b'\r')
def endswith_lf(line):
"""Return True if line (a text or bytestring) ends with '\n'."""
return line.endswith('\n' if isinstance(line, str) else b'\n')
def equals_lf(line):
"""Return True if line (a text or bytestring) equals '\n'."""
return line == ('\n' if isinstance(line, str) else b'\n')
